Apparatus for grinding internal surfaces



July 9, 1957 W. D. ROBERTS APPARATUS FOR GRINDING INTERNAL SURFACES Filed Sept. 22, 1955 3 Sheets-Sheet l w INVENTOR.

ILLJQM D. P055273 July 9, 1957' W. D. ROBERTS APPARATUS FOR GRINDING INTERNAL SURFACES Filed Sept. 22, 1955 3 Sheets-Sheet 2 INVEN TOR.

14.1.1001 0. Bazaars,

y 1957 w, D. ROBERTS 2,798,340 APPARATUS'FOR GRINDING INTERNAL SURFACES Filed Sept. 22. 1955 I 3 Sheets-Sheet 3 M [N VEN TOR.

144mm 0. ROBERTS 2,798,340 Patented July 9, 1957 2,798,540 APPARATUS FOR GRINDING INTERNAL SURFACES William D. Roberts, Pittsburgh, Pa., assignor to Ryman Engineering Company, Ellwood City, Pa., a corporation of Pennsylvania Application September 22, 1955, Serial No. 535,953

6 Claims. (Cl. 51-142) My invention relates to grinding apparatus, and more particularly to those of the sanding-belt type utilized in the grinding of hollow interior surfaces.

One object of my invention is to provide grinding apparatus that is particularly suitable for grinding interior surfaces of hemispherical or other concave forms, as well as in the grinding of inner tubular wall surfaces.

Another object of my invention is to provide grinding apparatus for the character referred to, wherein the sanding belt or a grinding wheel can readily be manipulated from one operative position to another operative position at right angles thereto, as for example in moving from a completely concave surface to an inner tubular surface, with means for effecting uniformity of grinding operation as between a hollow spherical surface and an inner tubular surface.

As shown in the accompanying drawings,

Figure 1 is a plan view of the machine;

Fig. 2 is a longitudinal sectional view therethrough;

Fig. 3 is a vertical cross sectional view;

Fig. 4 is a view showing the manner in which work pieces of various diameters may be supported; and

Fig. 5 is an enlarged sectional View, taken on the line V-V of Fig. 2.

The apparatus is particularly useful in the grinding and polishing where dense smooth surfaces are required as in connection with pharmaceutical containers, cooking vessels and food processing vessels, where even infinitesimal pits or fissures are objectionable.

As stated above, the apparatus is particularly suitable for the grinding of the interior surfaces of hemispheres and tubes. The numeral indicates a work piece that is of partially hollow hemisphere and cylindrical form and 11 the abrasive belt for surfacing the inner wall of the work piece.

The article 10 has a cradle-like support that comprises a pair of rollers 12 on one side and a pair of rollers 13 on the other side, the rollers having their bearings slidably adjustable on rails 14 to adapt them to work pieces of various diameters as indicated by dash lines in Fig. 4.

The rollers 13 are mounted on a shaft 15 that has a pulleyv 16 driven by a belt 17 from a pulley 18 of a motor 19 that is supported on a bracket arm 20 carried by one of the supports 21 for the roller shaft 15. The article is therefore rotated by the rollers at a desired speed. The motor 17 may be of a variable speed type, to provide a desired R. P. M. for the article.

A bed 22 has a housing formed thereon comprising a top plate 23 and a peripheral plate 24 welded to the base plate of the member 22. Posts 25 and 26 of jackscrew form are supported upon the plate 23 by collars 27 and 28 respectively, that are secured to the screws and rotate therewith. The screws at their upper ends have threaded connections with fixed bushings 2? as shown more clearly in Fig. 3, the screw 25 having a hand wheel 31 secured to its upper end and a sprocket gear wheel 32 secured to its lower end. A chain 33 extends around the sprocket 32 and around sprockets 34 that are secured to the lower ends of the screw posts 26. Skirts 35 having accordion-like folds seat at their upper and lower ends against the members 2% and 27 and are expansible and contractible to shield the screws against dirt, including the grindings from the Work pieces.

The bushings 29 support a base plate 36 which is raised and lowered by turning the hand wheel 31, to thereby position the abrasive belt and its supports symmetrically with respect to the axis of the work piece. A carriage 37 is slidably supported on the base plate and is movable longitudinally thereof by a screw 38 that is journaled in bearings 39 and 40 that are secured to the base plate 36 and extends through a threaded boss 41 which acts as a nut and is rigidly secured to the carriage 37.

The screw shaft 38 has a sprocket wheel 43 that is driven by a sprocket chain 44 from a motor 45, the motor being, of course, reversible to effect adjustments of the carriage 37, and to move it into and out of the work piece 10.

Since the abrasive belt and its supporting and operating mechanisms are movable with the carriage, they will thereby be shifted axially of the work piece, to bring the abrasive belt into contact with all of the wall surfaces.

The carriage 37 has an extension 47 formed integrally therewith and serving to support a head 4% in which a swivel member 49 is rotatably supported for oscillation about a vertical axis. Rods 56 are slidably supported in the swivel member 49, and at their outer ends carry a U-shaped bracket 51 that serves to support the shafts of idler rollers 52 and a presser roll 53 that backs up the abrasive belt 11. A cylinder 54- is carried by the swivel member 49 and has its piston 55 connected to a cross head 56 that is secured to the rods Stl. Fluid pressure is supplied to the cylinder 54 through suitable pipe connections. Yieldable pressure is thereby constantly exerted against the presser roll 53 to maintain the abrasive belt constantly in engagement with the working surface and to, of course, avoid chattering.

The abrasive belt is driven by a motor 60 through a V-belt or other suitable drive 61 that drives a pulley 62 which is secured to a shaft that carries a drum or pulley 63 which, in turn, drives the abrasive belt 11.

A bracket member 64 supports the shaft for the pulleys 62 and 63 and also supports the shafts of guide rollers 65 and 66 for the sanding belt. The bracket 64 and the motor 60 are mounted upon a plate 67 which is shiftable on the carriage 37 that has guide rods 37a for the plate. The plate 67 has connection at 68 with a cylinder 69 whose piston rod 70 is connected to an extension 71 of the plate 67, so as to adjust the tension of the sanding belt 11.

Tensioning of the driving belt 61 is effected by a screw 72 that is journaled on the plate 67 and has a hand wheel 73. The screw has threaded engagement with a boss 74 that is carried by the base plate '75 of the motor 60, which is slidable on the member 67.

With the parts in the position shown in Fig. 2 and the sanding belt being driven simultaneously with rotation of the work piece 18, the grinding operation will be commenced adjacent to the center of the curved surface.

The swivel members 59 and the rods 5t; that carry the bracket 51 will immediately be started on their swinging movement toward the position shown in Fig. l, the swinging movement or the rate of rotation of the work piece about its axis will initially be somewhat rapid relative to the rate of movement at a later stage, to avoid overgrinding of the central area of the hemispherical surface.

Swinging movement of the swivel 45 and the bracket 51 that carries the abrasive belt pulleys 52 and 53 is et q ed b a w m st r fit! ame by the lower n the swivel member 49 and driven by 'a w orm 81 whose shaft 82 carries a sprocket wheel 83 driven by a chain 9 a ia lh he t! ha 8, a y el hhqwh yre ha l r duall hd h ts rh dhe h e a he mo hr a d h t rat t sw ns ha thh th h Qt the sanding belt at the bracket 51 will gradually be r511 duced as the sanding belt approaches the position shgwn by full lines in Fig. l, in order to insure that the grinding will be uniform at all areas.

In grinding the cylindrical surface rearwardly of the hemispherical surface, the sanding belt will be maintained in the position shown in Fig. l and the carriage shifted rearwardly by the motor 45 and the screw 38, to move the sanding belt in a withdrawing direction relative to the work piece. 7

I11 order that the sanding belt 11 may be driven not only in its generally straight-line direction shown in Fig. 2, but also in a direction at a right angle thereto, as shown in Fig. 1, guide pulleys 86 are provided therefor, having belt-engaging peripheries that twist the belt about 45 relative to what would be the natural or normal plane of the belt at that vicinity if these pulleys were not present.

The swinging movements of the bracket 51 are automatically limited by micro-switches 88 and 89 that are respectively automatically operated by a stud 90 at each of the extreme positions of swinging movement shown in Fig. 1, to respectively stop the motor 85 and thus end the swinging movement when the belt has reached either of its positions shown in Fig. 1.

I claim as may invention:

1. Grinding apparatus comprising a support for a work piece, an abrasive belt in the form of an elongated loop, a driving pulley in one end of the loop, a bracket carrying a presser pulley in the outer end of the loop, a swivel member which at its forward end supports the bracket, means for pivotally supporting the rear end of the swivel member on an axis perpendicular to the planes of the belt runs, and at a point between the pulleys, guide pulleys adjacent to the said axis, in position to deflect the belt runs to a direction transverse to their lines of travel between the driving pulley and the rear end of the swivel member, the guide pulleys whose beltengaging peripheries are inclined at approximately 45 degrees relative to the planes of the belt runs at said driving pulley and presser pulley and at such angles that each of the belt runs between the guide pulleys and the presser pulleys has its edges maintained under equal stress and the working area of the belt at the outer end of the belt loop has full-width engagement with work pieces on the support, at all positions of the swivel member.

2. Apparatus as recited in claim 1, wherein a carriage supports the driving pulley and bracket and means are provided for reciprocating the carriage to move the bracket into and out of hollow work pieces and for adjusting the carriage to various positions transversely of its path of reciprocation.

3. Apparatus for grinding the interior surfaces of hollow hemispherical articles, comprising means for supporting an article for rotation about its axis, a carriage movable axially toward the article, when so supported, an abrasive belt of elongated loop form," a pulley on the carriage for driving the abrasive belt, a bracket pivotally mounted on the carriage in position to be moved into the article, and projecting forwardly from the carriage, a belt presser and guide roll on the forward end of the bracket, for directing the runs of the abrasive belt in its looped path and holding itf again st the interior s urface of the article, means for oscillating the bracket on its pivotal mounting, about an axis transverse to the axis of th artigle, and ot er uidepu lys, a t e rea end ofv the bracket, in position to guide those. portions of the belt. hhs ttw th h piv talmhhhtih a he belt presser from a path parallel to the axis of the article toward and from a path transverse to said axis, during swinging movement of the bracket on its pivotal mountmg.

4- A ratu a r cit d in l m 3 wherein th a u de pull ys, have eir beleeh a h surfaces. of su angularity that the belt runs will be deflected in the vicinity of these pulleys to planes that are inclined with r spect to he p a es o c pie y the e a he dr vin pulley and the presser roll.

5. Apparatus for grinding the interior surfaces of hollow hemispherical articles, comprising means for supporting an article. for rotation about its axis, a carriage mov :able axially toward the article, when so supported, an abrasive belt of elongated loop form, a pulley on the carriage for driving the abrasive belt, a bracket pivotally mounted on the carriage in position to be moved into the article, and projecting forwardly from the carriage, guide pulleys on the forward end of the bracket, for directing the runs of the abrasive belt in a looped path, a presser roll between the guide pulleys, holding the belt against the interior surface of the article, the bracket being oscillatable on its pivotal mounting, about an axis transverse to the axis of the article, and other guide pulleys on the'rear end of the bracket and at opposite sides of its pivotal mounting, and having their belt-engaging surfaces inclined relative to the axes of the driving'and guide pulleys, in position to guide the belt runs from a path parallel to the axis of the'articleto and from a path transverse to said axis. i

6. Apparatus as recited in claim 5, wherein the firstnamed guide pulleys are yieldably held in outwardlyprojected position relative to the said pivotal mounting, at all positions of the bracket on its pivotal mounting.

References Cited in the file of this patent UNI EP S ATES EN 

